Windows 2003 crashing when enabling /3GB

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Massimo

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I've been working a cluster of two Windows 2003 Enterprise SP2 systems,
which run SQL Server and are also domain controllers for a local domain
(it's an hosted environment, so only two servers could be fitted there). The
two servers have each 18 GB of memory, but run the x86 Windows version.

The /PAE switch is enabled on those systems, in order to take advantage of
all that memory; today, we tried enabling the /3GB switch too, to give SQL
Server some extra memory... but then the systems started behaving
erratically, taking hours (literally!) to start up, even more time to log
on, showing plenty of errors in the event log about almost everything
crashing randomly and not letting you starting any program when you finally
got to the desktop; a typical memory error condition. This happened on the
passive cluster node, on which we tried the new settings, so it was not
related to SQL Server at all.

Everything went back to normal when the /3GB switch was removed.

Why is this happening? I've found some articles stating that the /3GB switch
can cause problems with memory-hungry device drivers, such as 3D video
cards, but those are server systems and most definitely don't have that kind
of hardware; I've also read that due to page table problems, you can't use
more than 16 GB of memory when both /PAE and /3GB are enabled; so I tried
removing 2 GB of memory from them, but the problem persisted: when /3GB is
enabled, the systems gets completely unstable. When only /PAE is enabled,
everything works fine, but (obviously) programs can't use more than 2 GB
each.

I've enable both /3GB and /PAE on other systems without having any problem,
but they had less physical memory, and they were also not domain
controllers. Could this be a problem of kernel memory exhaustion due to
excessive page table usage and/or kernel memory requirements of the domain
controller role?


Can someone please help?


Thanks


Massimo
 
Re: Windows 2003 crashing when enabling /3GB

Hello Massimo,

Better post this to:
microsoft.public.windows.server.clustering

Best regards

Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
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> I've been working a cluster of two Windows 2003 Enterprise SP2
> systems, which run SQL Server and are also domain controllers for a
> local domain (it's an hosted environment, so only two servers could be
> fitted there). The two servers have each 18 GB of memory, but run the
> x86 Windows version.
>
> The /PAE switch is enabled on those systems, in order to take
> advantage of all that memory; today, we tried enabling the /3GB switch
> too, to give SQL Server some extra memory... but then the systems
> started behaving erratically, taking hours (literally!) to start up,
> even more time to log on, showing plenty of errors in the event log
> about almost everything crashing randomly and not letting you starting
> any program when you finally got to the desktop; a typical memory
> error condition. This happened on the passive cluster node, on which
> we tried the new settings, so it was not related to SQL Server at all.
>
> Everything went back to normal when the /3GB switch was removed.
>
> Why is this happening? I've found some articles stating that the /3GB
> switch can cause problems with memory-hungry device drivers, such as
> 3D video cards, but those are server systems and most definitely don't
> have that kind of hardware; I've also read that due to page table
> problems, you can't use more than 16 GB of memory when both /PAE and
> /3GB are enabled; so I tried removing 2 GB of memory from them, but
> the problem persisted: when /3GB is enabled, the systems gets
> completely unstable. When only /PAE is enabled, everything works fine,
> but (obviously) programs can't use more than 2 GB each.
>
> I've enable both /3GB and /PAE on other systems without having any
> problem, but they had less physical memory, and they were also not
> domain controllers. Could this be a problem of kernel memory
> exhaustion due to excessive page table usage and/or kernel memory
> requirements of the domain controller role?
>
> Can someone please help?
>
> Thanks
>
> Massimo
>
 
Re: Windows 2003 crashing when enabling /3GB

>I've been working a cluster of two Windows 2003 Enterprise SP2 systems,
>which run SQL Server and are also domain controllers for a local domain
>(it's an hosted environment, so only two servers could be fitted there). The
>two servers have each 18 GB of memory, but run the x86 Windows version.
>
>The /PAE switch is enabled on those systems, in order to take advantage of
>all that memory; today, we tried enabling the /3GB switch too, to give SQL
>Server some extra memory... but then the systems started behaving
>erratically, taking hours (literally!) to start up, even more time to log
>on, showing plenty of errors in the event log about almost everything
>crashing randomly and not letting you starting any program when you finally
>got to the desktop; a typical memory error condition. This happened on the
>passive cluster node, on which we tried the new settings, so it was not
>related to SQL Server at all.
>
>Everything went back to normal when the /3GB switch was removed.
>
>Why is this happening? I've found some articles stating that the /3GB switch
>can cause problems with memory-hungry device drivers, such as 3D video
>cards, but those are server systems and most definitely don't have that kind
>of hardware; I've also read that due to page table problems, you can't use
>more than 16 GB of memory when both /PAE and /3GB are enabled; so I tried
>removing 2 GB of memory from them, but the problem persisted: when /3GB is
>enabled, the systems gets completely unstable. When only /PAE is enabled,
>everything works fine, but (obviously) programs can't use more than 2 GB
>each.
>
>I've enable both /3GB and /PAE on other systems without having any problem,
>but they had less physical memory, and they were also not domain
>controllers. Could this be a problem of kernel memory exhaustion due to
>excessive page table usage and/or kernel memory requirements of the domain
>controller role?

From what I can tell, enabling /3GB will limit you to 16GB (of your
18GB) only so maybe you might not even need /3GB? See the chart info
from this page:
http://support.microsoft.com/kb/291988

Not sure how useful it'd be but how about implementing the /USERVA
switch and setting it around 2944 for starters? Read the info in
http://support.microsoft.com/kb/316739, especially pay attention to
the part: "Note Microsoft Product Support Services strongly recommends
using a range of memory for the /userva=xxxx switch that is within the
range of 2900 to 3030. This range is wide enough to provide a pool of
system PTEs that is large enough for all currently observed issues."
I use 2944 in my own environment and it's seems like a decent middle
ground. Try that and see if it helps you any.

What version of SQL?

I also recommend the following two article:

http://blogs.technet.com/askperf/archive/2007/03/23/memory-management-demystifying-3gb.aspx
http://support.microsoft.com/kb/291988

- Thee Chicago Wolf
 
Re: Windows 2003 crashing when enabling /3GB

"Meinolf Weber" <meiweb(nospam)@gmx.de> ha scritto nel messaggio
news:ff16fb66a15f8cafccb4fc567b0@msnews.microsoft.com...

> Hello Massimo,
>
> Better post this to:
> microsoft.public.windows.server.clustering

Why? It doesn't seem to be a cluster-related problem at all...


Massimo
 
Re: Windows 2003 crashing when enabling /3GB

"Thee Chicago Wolf" <.@.> ha scritto nel messaggio
news:0jobf4tku7qcquvfhl69c496kcuk3kqsdi@4ax.com...

> Not sure how useful it'd be but how about implementing the /USERVA
> switch and setting it around 2944 for starters? Read the info in
> http://support.microsoft.com/kb/316739, especially pay attention to
> the part: "Note Microsoft Product Support Services strongly recommends
> using a range of memory for the /userva=xxxx switch that is within the
> range of 2900 to 3030. This range is wide enough to provide a pool of
> system PTEs that is large enough for all currently observed issues."
> I use 2944 in my own environment and it's seems like a decent middle
> ground. Try that and see if it helps you any.

That could be a good suggestion; unfortunately, we can't do much testing,
since that's a production environmente... but I'll keep it in mind; that
erratic behaviour could very well be the result of a PTE shortage.

Anyway, we migrated the database cluster to SQL Server 2005... so maybe
enabling AWE will be enough.


Massimo
 
Re: Windows 2003 crashing when enabling /3GB

>"Thee Chicago Wolf" <.@.> ha scritto nel messaggio
>news:0jobf4tku7qcquvfhl69c496kcuk3kqsdi@4ax.com...
>
>> Not sure how useful it'd be but how about implementing the /USERVA
>> switch and setting it around 2944 for starters? Read the info in
>> http://support.microsoft.com/kb/316739, especially pay attention to
>> the part: "Note Microsoft Product Support Services strongly recommends
>> using a range of memory for the /userva=xxxx switch that is within the
>> range of 2900 to 3030. This range is wide enough to provide a pool of
>> system PTEs that is large enough for all currently observed issues."
>> I use 2944 in my own environment and it's seems like a decent middle
>> ground. Try that and see if it helps you any.
>
>That could be a good suggestion; unfortunately, we can't do much testing,
>since that's a production environmente... but I'll keep it in mind; that
>erratic behaviour could very well be the result of a PTE shortage.
>
>Anyway, we migrated the database cluster to SQL Server 2005... so maybe
>enabling AWE will be enough.

Yes, I understand about it being production environment. It's still no
good if it's crashing for those using it. If you try it out, let us
know how it goes. Also, SQL fully patched up too?

- Thee Chicago Wolf
 
Re: Windows 2003 crashing when enabling /3GB

"Thee Chicago Wolf" <.@.> ha scritto nel messaggio
news:pgdcf4971b2h8n3ocdme6upcr9b10p6pb7@4ax.com...

> Yes, I understand about it being production environment. It's still no
> good if it's crashing for those using it. If you try it out, let us
> know how it goes. Also, SQL fully patched up too?

Yes, of course. We're currently discussing with the end customer about
enabling AWE, I'll let you know how things go.


Massimo
 
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